2 * MOV, 3GP, MP4 muxer RTP hinting
3 * Copyright (c) 2010 Martin Storsjo
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include "libavutil/intreadwrite.h"
25 #include "rtpenc_chain.h"
27 int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
29 MOVMuxContext *mov = s->priv_data;
30 MOVTrack *track = &mov->tracks[index];
31 MOVTrack *src_track = &mov->tracks[src_index];
32 AVStream *src_st = s->streams[src_index];
33 int ret = AVERROR(ENOMEM);
35 track->tag = MKTAG('r','t','p',' ');
36 track->src_track = src_index;
38 track->enc = avcodec_alloc_context();
41 track->enc->codec_type = AVMEDIA_TYPE_DATA;
42 track->enc->codec_tag = track->tag;
44 track->rtp_ctx = ff_rtp_chain_mux_open(s, src_st, NULL,
49 /* Copy the RTP AVStream timebase back to the hint AVStream */
50 track->timescale = track->rtp_ctx->streams[0]->time_base.den;
52 /* Mark the hinted track that packets written to it should be
53 * sent to this track for hinting. */
54 src_track->hint_track = index;
57 av_log(s, AV_LOG_WARNING,
58 "Unable to initialize hinting of stream %d\n", src_index);
59 av_freep(&track->enc);
60 /* Set a default timescale, to avoid crashes in av_dump_format */
61 track->timescale = 90000;
66 * Remove the first sample from the sample queue.
68 static void sample_queue_pop(HintSampleQueue *queue)
72 if (queue->samples[0].own_data)
73 av_free(queue->samples[0].data);
75 memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
79 * Empty the sample queue, releasing all memory.
81 static void sample_queue_free(HintSampleQueue *queue)
84 for (i = 0; i < queue->len; i++)
85 if (queue->samples[i].own_data)
86 av_free(queue->samples[i].data);
87 av_freep(&queue->samples);
93 * Add a reference to the sample data to the sample queue. The data is
94 * not copied. sample_queue_retain should be called before pkt->data
97 static void sample_queue_push(HintSampleQueue *queue, AVPacket *pkt, int sample)
99 /* No need to keep track of smaller samples, since describing them
100 * with immediates is more efficient. */
103 if (!queue->samples || queue->len >= queue->size) {
106 samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
109 queue->samples = samples;
111 queue->samples[queue->len].data = pkt->data;
112 queue->samples[queue->len].size = pkt->size;
113 queue->samples[queue->len].sample_number = sample;
114 queue->samples[queue->len].offset = 0;
115 queue->samples[queue->len].own_data = 0;
120 * Make local copies of all referenced sample data in the queue.
122 static void sample_queue_retain(HintSampleQueue *queue)
125 for (i = 0; i < queue->len; ) {
126 HintSample *sample = &queue->samples[i];
127 if (!sample->own_data) {
128 uint8_t* ptr = av_malloc(sample->size);
130 /* Unable to allocate memory for this one, remove it */
131 memmove(queue->samples + i, queue->samples + i + 1,
132 sizeof(HintSample)*(queue->len - i - 1));
136 memcpy(ptr, sample->data, sample->size);
138 sample->own_data = 1;
145 * Find matches of needle[n_pos ->] within haystack. If a sufficiently
146 * large match is found, matching bytes before n_pos are included
147 * in the match, too (within the limits of the arrays).
149 * @param haystack buffer that may contain parts of needle
150 * @param h_len length of the haystack buffer
151 * @param needle buffer containing source data that have been used to
153 * @param n_pos start position in needle used for looking for matches
154 * @param n_len length of the needle buffer
155 * @param match_h_offset_ptr offset of the first matching byte within haystack
156 * @param match_n_offset_ptr offset of the first matching byte within needle
157 * @param match_len_ptr length of the matched segment
158 * @return 0 if a match was found, < 0 if no match was found
160 static int match_segments(const uint8_t *haystack, int h_len,
161 const uint8_t *needle, int n_pos, int n_len,
162 int *match_h_offset_ptr, int *match_n_offset_ptr,
166 for (h_pos = 0; h_pos < h_len; h_pos++) {
168 int match_h_pos, match_n_pos;
170 /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
171 while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
172 needle[n_pos + match_len] == haystack[h_pos + match_len])
177 /* If a sufficiently large match was found, try to expand
178 * the matched segment backwards. */
181 while (match_n_pos > 0 && match_h_pos > 0 &&
182 needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
189 *match_h_offset_ptr = match_h_pos;
190 *match_n_offset_ptr = match_n_pos;
191 *match_len_ptr = match_len;
198 * Look for segments in samples in the sample queue matching the data
199 * in ptr. Samples not matching are removed from the queue. If a match
200 * is found, the next time it will look for matches starting from the
201 * end of the previous matched segment.
203 * @param data data to find matches for in the sample queue
204 * @param len length of the data buffer
205 * @param queue samples used for looking for matching segments
206 * @param pos the offset in data of the matched segment
207 * @param match_sample the number of the sample that contained the match
208 * @param match_offset the offset of the matched segment within the sample
209 * @param match_len the length of the matched segment
210 * @return 0 if a match was found, < 0 if no match was found
212 static int find_sample_match(const uint8_t *data, int len,
213 HintSampleQueue *queue, int *pos,
214 int *match_sample, int *match_offset,
217 while (queue->len > 0) {
218 HintSample *sample = &queue->samples[0];
219 /* If looking for matches in a new sample, skip the first 5 bytes,
220 * since they often may be modified/removed in the output packet. */
221 if (sample->offset == 0 && sample->size > 5)
224 if (match_segments(data, len, sample->data, sample->offset,
225 sample->size, pos, match_offset, match_len) == 0) {
226 *match_sample = sample->sample_number;
227 /* Next time, look for matches at this offset, with a little
228 * margin to this match. */
229 sample->offset = *match_offset + *match_len + 5;
230 if (sample->offset + 10 >= sample->size)
231 sample_queue_pop(queue); /* Not enough useful data left */
235 if (sample->offset < 10 && sample->size > 20) {
236 /* No match found from the start of the sample,
237 * try from the middle of the sample instead. */
238 sample->offset = sample->size/2;
240 /* No match for this sample, remove it */
241 sample_queue_pop(queue);
247 static void output_immediate(const uint8_t *data, int size,
248 AVIOContext *out, int *entries)
254 avio_w8(out, 1); /* immediate constructor */
255 avio_w8(out, len); /* amount of valid data */
256 avio_write(out, data, len);
260 for (; len < 14; len++)
267 static void output_match(AVIOContext *out, int match_sample,
268 int match_offset, int match_len, int *entries)
270 avio_w8(out, 2); /* sample constructor */
271 avio_w8(out, 0); /* track reference */
272 avio_wb16(out, match_len);
273 avio_wb32(out, match_sample);
274 avio_wb32(out, match_offset);
275 avio_wb16(out, 1); /* bytes per block */
276 avio_wb16(out, 1); /* samples per block */
280 static void describe_payload(const uint8_t *data, int size,
281 AVIOContext *out, int *entries,
282 HintSampleQueue *queue)
284 /* Describe the payload using different constructors */
286 int match_sample, match_offset, match_len, pos;
287 if (find_sample_match(data, size, queue, &pos, &match_sample,
288 &match_offset, &match_len) < 0)
290 output_immediate(data, pos, out, entries);
293 output_match(out, match_sample, match_offset, match_len, entries);
297 output_immediate(data, size, out, entries);
301 * Write an RTP hint (that may contain one or more RTP packets)
302 * for the packets in data. data contains one or more packets with a
305 * @param out buffer where the hints are written
306 * @param data buffer containing RTP packets
307 * @param size the size of the data buffer
308 * @param trk the MOVTrack for the hint track
309 * @param pts pointer where the timestamp for the written RTP hint is stored
310 * @return the number of RTP packets in the written hint
312 static int write_hint_packets(AVIOContext *out, const uint8_t *data,
313 int size, MOVTrack *trk, int64_t *pts)
316 int64_t count_pos, entries_pos;
317 int count = 0, entries;
319 count_pos = url_ftell(out);
320 /* RTPsample header */
321 avio_wb16(out, 0); /* packet count */
322 avio_wb16(out, 0); /* reserved */
325 uint32_t packet_len = AV_RB32(data);
331 if (packet_len > size || packet_len <= 12)
333 if (data[1] >= 200 && data[1] <= 204) {
334 /* RTCP packet, just skip */
340 if (packet_len > trk->max_packet_size)
341 trk->max_packet_size = packet_len;
343 seq = AV_RB16(&data[2]);
344 ts = AV_RB32(&data[4]);
346 if (trk->prev_rtp_ts == 0)
347 trk->prev_rtp_ts = ts;
348 /* Unwrap the 32-bit RTP timestamp that wraps around often
349 * into a not (as often) wrapping 64-bit timestamp. */
350 trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
351 trk->prev_rtp_ts = ts;
352 if (*pts == AV_NOPTS_VALUE)
353 *pts = trk->cur_rtp_ts_unwrapped;
356 /* RTPpacket header */
357 avio_wb32(out, 0); /* relative_time */
358 avio_write(out, data, 2); /* RTP header */
359 avio_wb16(out, seq); /* RTPsequenceseed */
360 avio_wb16(out, 0); /* reserved + flags */
361 entries_pos = url_ftell(out);
362 avio_wb16(out, 0); /* entry count */
369 /* Write one or more constructors describing the payload data */
370 describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
374 curpos = url_ftell(out);
375 avio_seek(out, entries_pos, SEEK_SET);
376 avio_wb16(out, entries);
377 avio_seek(out, curpos, SEEK_SET);
380 curpos = url_ftell(out);
381 avio_seek(out, count_pos, SEEK_SET);
382 avio_wb16(out, count);
383 avio_seek(out, curpos, SEEK_SET);
387 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
388 int track_index, int sample)
390 MOVMuxContext *mov = s->priv_data;
391 MOVTrack *trk = &mov->tracks[track_index];
392 AVFormatContext *rtp_ctx = trk->rtp_ctx;
395 AVIOContext *hintbuf = NULL;
400 return AVERROR(ENOENT);
402 return AVERROR(ENOMEM);
404 sample_queue_push(&trk->sample_queue, pkt, sample);
406 /* Feed the packet to the RTP muxer */
407 ff_write_chained(rtp_ctx, 0, pkt, s);
409 /* Fetch the output from the RTP muxer, open a new output buffer
411 size = url_close_dyn_buf(rtp_ctx->pb, &buf);
412 if ((ret = url_open_dyn_packet_buf(&rtp_ctx->pb,
413 RTP_MAX_PACKET_SIZE)) < 0)
419 /* Open a buffer for writing the hint */
420 if ((ret = url_open_dyn_buf(&hintbuf)) < 0)
422 av_init_packet(&hint_pkt);
423 count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
426 /* Write the hint data into the hint track */
427 hint_pkt.size = size = url_close_dyn_buf(hintbuf, &buf);
429 hint_pkt.pts = hint_pkt.dts;
430 hint_pkt.stream_index = track_index;
431 if (pkt->flags & AV_PKT_FLAG_KEY)
432 hint_pkt.flags |= AV_PKT_FLAG_KEY;
434 ff_mov_write_packet(s, &hint_pkt);
437 sample_queue_retain(&trk->sample_queue);
441 void ff_mov_close_hinting(MOVTrack *track) {
442 AVFormatContext* rtp_ctx = track->rtp_ctx;
445 av_freep(&track->enc);
446 sample_queue_free(&track->sample_queue);
450 av_write_trailer(rtp_ctx);
451 url_close_dyn_buf(rtp_ctx->pb, &ptr);
454 avformat_free_context(rtp_ctx);